Various techniques and systems have been proposed for modification of biorhythmic activity. The following patents are believed to represent the state of the prior art: U.S. Pat. No. 5,267,942 to Saperston, entitled Method For Influencing Physiological Processes Through Physiologically Interactive Simuli. U.S. Pat. No. 5,076,281 to Gavish, the present inventor, entitled Device and Method for Effecting Rhythmic Body Activity. Further relevant prior art appears in the References Cited listings of the aforesaid patents and in the Background sections thereof. U.S. Pat. No. 5,423,328 also to Gavish describes a monitoring device which is particularly suitable for use in the present invention. The disclosures of all of these patents are hereby incorporated by reference.